First I present three problems that all involve a discount. The first asks for the discount percentage, the second for the discount price, and the third for the original price.

Then I also solve a problem where the original price and a percentage price increase are given, and the new price is asked.

One basic principle that helps you solve these is this "formula": PART/TOTAL = PERCENTAGE. The first problem where a $14 shirt is discounted by $2 is solved by using that: the discount percent is found by converting the fraction 2/14 into a percentage.

I solve the second problem in two ways: first, by finding 10% of the original price, doubling that to find 20% of it, and lastly subtracting the result from the original price to get the discounted price. I also use the thought that if an item is discounted by 20%, then 80% of the price is left, so we can simply calculate 0.8 x $14 to get the new, discounted price.

And to find the original price when the discount percentage and the discount amount are known, once again, PART/TOTAL = PERCENTAGE would work. Or, we can reason that if $3 is 15% of it, then $1 is 5% of it, and therefore 20 is 100% of it.

The 2nd part of this lesson is at https://www.youtube.com/watch?v=mH_Bx2oX4Mg

This lesson is meant for 7th grade or pre-algebra.

Tagged under: percentage,percent problems,percent word problems,discount price,discount percentage,original price,pre-algebra,grade 7,math,percent,discount

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